Abstract

This paper presents some results achieved from a preliminary study on the use
of the Ant Colony Algorithm to plan feasible optimal or suboptimal trajectories
for an autonomous ship manoeuvring. The scenario, for this preliminary work,
comprises only open sea manoeuvres. The goal involves obtaining the least
time consuming ship trajectory between to points, departing from the start
point with arbitrary initial speed and attitude values and arriving to the end
point with predefined speed and attitude values.
The specific dynamic of the ship imposes typical restrictions to its manoeuvrability.
In the present case, the non-holonomicity, the rate speed/turn radius,
and the imposed forward-only propulsion of the ship make up the main restrictions
to the ship movement. For long distances, the problem could be tackled
as a classical navigation problem, in which, for the most part of the ship
trajectory, techniques such inertial navigation should be enough. The problem
arises at short distances when it becomes a manoeuvring problem. In this case
to obtain a optimal, --in some cases just a feasible--, trajectory could be a difficult
problem.